In the past it has been common to discharge waste materials from a mercury-cell chlorine process into a large settling pond or lagoon, where the solid materials are allowed to settle while the liquid is pumped out for reprocessing. According to present day environmental standards, however, such discharge techniques are highly undesirable. An expensive alternative is to dispose of the toxic waste material by loading it into containers, double-lined with PVC, and dumping the containers in a secured landfill provided with a leachate collection system. Also, reports indicate that attempts have been made, in conjunction with the spending of millions of dollars of federal research funds, to process such waste sludges on a batch basis in rotary hearth ovens, in an effort to reduce the mercury content to a tolerable level. However, it is understood that such attempts have been practical failures because of inadequate recovery of the mercury, followed by total failure of the apparatus due to corrosion and disintegration of various necessary elements thereof.